The subject matter of the present invention relates generally to a desiccant device for removing moisture from air supplied to the rotor bearings of motors, pumps, gear reducers and the like, to prevent such bearings from rusting. In particular, the preferred embodiment of such bearing breather desiccant device is provided with one or more outlet tubes which are connected to the lubrication fittings of the equipment containing the bearings so that any air supplied to such bearings must be transmitted through the desiccant. The present invention is especially useful in preventing the rotor bearings of electrical motors from rusting.
Previously, electrical motors, pumps, gear reducers and other apparatus having rotor bearings have suffered from the problem of bearing rust during storage or other periods of nonuse. This is caused by moisture condensing from the air onto the bearings when the temperature of the bearings falls below the dew point. Previously electrical heaters have been installed around the bearings to keep their temperatures above the dew point. Another solution has been to hermetically seal the equipment to prevent moisture laden air from reaching the bearings. However, both of these solutions are extremely expensive and cannot be employed on smaller motors, pumps and other relatively inexpensive equipment. Therefore, it has previously been the practice in these cases for a maintenance person to manually rotate the rotor shafts of the equipment every week in order to recoat the bearings with lubricant. Unfortunately this is not effective for the most part especially when the equipment is stored in direct sunlight or in a shed which is heated by the sun, because such heat causes the grease or oil used as a lubricant to drain away very quickly from the recoated bearings, often within one day. As a result, moisture condenses on the nonlubricated surfaces of the bearings, and rusting results before the shaft can be rotated manually again.
The bearing breather desiccant device of the present invention will reduce the moisture in the air supplied to the bearings and thereby prevent such bearings from rusting. All openings other than the lubrication fittings to which the tubes of the desiccant device are connected must be sealed to force the equipment to breathe air through the desiccant device. It should be noted that during nonuse equipment bearings breathe as a result of expansion and contraction of the air due to changes in the ambient temperature. The invention has the added advantage of being relatively inexpensive and easy to install on the equipment being protected. Of course, the desiccant device must be replaced when it has absorbed so much moisture that it no longer operates efficiently. This is indicated by a change in color of the desiccant which can be viewed through the wall of a transparent plastic bag containing such desiccant. While the desiccant device of the present invention greatly reduces the amount of moisture which can condense on the bearings, for added protection the rotor shafts of the motors and other equipment should still be manually rotated at regular intervals.
Previously, desiccant devices have been used in the lines of refrigerant systems to remove moisture from the refrigerant fluid, as shown in U.S. Pat. No. 3,734,296 of Proctor et al and U.S. Pat. No. 3,979,292 of McClive. It has been suggested to use a chemical moisture indicator in the desiccant device of such refrigeration systems, which changes color to visually indicate the amount of moisture absorbed, as discussed in U.S. Pat. No. 3,246,758 of Wagner. However, none of these patents suggest that a desiccant device can be used to prevent the rotor bearings of motors, pumps, gear reducers and like equipment from rusting by connecting air outlet tubes of the device to the lubrication fittings of the bearings and sealing all other air openings to the bearings in the manner of the present invention.